1. Field of the Invention
This invention relates to a copying apparatus in which a sheet-like original transport unit is rotatable for repeated exposure of the sheet-like original. More particularly, it relates to a copying apparatus capable of copying both sheet-like originals and book-like originals in which the sheet-like original transport unit is rotatable to permit both sides of sheet-like originals to be copied continuously.
2. Description of the Prior Art
The copying apparatus of the type in which a book-like original may be placed in position on an original carriage and scanned in the lateral direction by an image-forming optical system has an advantage that does not require great dimensions for allowing movement of the original carriage, unlike the copying apparatus of the movable original carriage type. However, where a book-like original is to be copied, the copying apparatus of such type requires the image-forming optical system to be returned to its initial position during each exposure of the original and thus, it is disadvantageous in that the time required for copying is sharply increased particularly when multiple copies are desired.
Therefore, such a scanning method has been used chiefly for the exposure of book-like originals and not sheet-like originals. In contrast, sheet-like originals are guided through a reading window by a transport roll mechanism and this can be done continuously. During the copying of sheet-like originals, the image-forming optical system remains stationary as a rule. The optical system is used for the copying of book-like and sheet-like originals. The image-forming optical system is usually movable only along the scanning stroke and therefore, when the copying method (book copy or sheet copy) is changed, the apparatus must be prepared for such change. In the known apparatus, the book-like original carriage is designed for movement with the sheet-like original transport mechanism and thus, when sheet-like originals are to be copied, the image-forming window for sheets is positioned at the starting point of the scanning stroke. For the book copy, the book-like original carriage and the sheet transport mechanism are again returned to their initial positions. Such system requires undesirable expenses.
Also, where both sides of a sheet original are to be copied, termination of the first scanning must be followed by the transport of the sheet original to the same sheet transport mechanism. This is time-consuming.